Link against pthreads library on systems that do not include it automatically. Fixes issue 149.
Link against pthreads library on systems that do not include it automatically. Fixes issue 149.

joechenq/nvidia-texture-tools,tectronics/nvidia-texture-tools,tectronics/nvidia-texture-tools,y2jinc/nvidia-texture-tools,y2jinc/nvidia-texture-tools,fynv/nvidia-texture-tools,rabidflea/nvidia-texture-tools,dmsovetov/nvidia-texture-tools,fynv/nvidia-texture-tools,tectronics/nvidia-texture-tools,y2jinc/nvidia-texture-tools,dmsovetov/nvidia-texture-tools,dmsovetov/nvidia-texture-tools,Ghost-yc/nvidia-texture-tools,joechenq/nvidia-texture-tools,dmsovetov/nvidia-texture-tools,joechenq/nvidia-texture-tools,fynv/nvidia-texture-tools,fynv/nvidia-texture-tools,Ghost-yc/nvidia-texture-tools,Ghost-yc/nvidia-texture-tools,Ghost-yc/nvidia-texture-tools,rabidflea/nvidia-texture-tools,rabidflea/nvidia-texture-tools,y2jinc/nvidia-texture-tools,tectronics/nvidia-texture-tools,joechenq/nvidia-texture-tools,rabidflea/nvidia-texture-tools